The ability to compare objects according to discrete dimensions such as size, color or shape seems basic to human intelligence. However, developmental research indicates that knowledge of dimensions is complex and emerges gradually throughout the preschool and early school years. We propose here a componential model in which an understanding of attribute, dimension, directionality and continuity comprises the structural core of dimensional knowledge. The proposed project tests the developmental independence of these components and their order of acquisition. Performance in verbal and nonverbal tasks will be compared to provide a complete description of the development of dimensional concepts. Certain aspects of this growth may reflect experience with objects, other aspects may reflect experience with language. Forty normal children aged 2-5 and twenty language disordered children aged 3-7 will participate in each of three experiments designed to assess the understanding of size and brightness dimensions. The three experiments examine knowledge of (1) attributes and dimensions, (2) directionality and dimensions, (3) continuity. Each experiment presents parallel verbal and nonverbal tasks. In the nonverbal tasks children demonstrate their knowledge by selecting objects(s) which correspond to the experimenters' models in dimensional character though they differ in absolute physical properties. In the verbal tasks children follow directions for object selection, e.g. "Find the big one." Language disordered children, whose language learning lags behind other aspects of development, will provide a view of cognitive growth relatively uneffected by semantic knowledge. The project, by looking closely at both conceptual and linguistic domains, will also clarify the nature of intellectual development in this population. Speech-language pathologists, special educators and psychologists can make use of this information in planning curriculum for this educationally perplexing group. Moreover, since aspects of dimensional knowledge are crucial components of mathematics and inferential reasoning, this project will contribute to educational programming for all children.